1. Field of the Invention
The present invention relates to multi-layer coating apparatuses and, particularly, to a multilayer coating apparatus for delivering coating materials to a surface of an object.
2. Discussion of the Related Art
A coating apparatus is for applying a coating material onto a surface of an object. The coating apparatus is usually required to be capable of controlling a flux or other coating material flowing to the surface, a flow velocity, a relative moving velocity between the surface of the object and the coating apparatus, and a distance between the object and the coating apparatus, in order to control a thickness of the coating material formed on the object and to distribute the coating material evenly on the surface of the object. In general, in many circumstances, a plurality of layers of the various coating materials is required to be coated/formed on an object. For example, a photosensitive composite film stack usually includes nine or more layers of materials. Thus, a multilayer coating apparatus that is capable of simultaneously coating a plurality of layers of materials is demanded.
In order to improve the coating quality, many modifications have been made to the coating apparatus. For example, an unfluctuating rolling edge has been proposed to sustain a flux of the liquid flowing on the slide surface, and/or an inhaled air removal device has been devised for eliminating an excess of inhaled air brought into the coating area by the moving object.
Slide hoppers are often employed in such multilayer coating apparatuses for supplying and guiding the coating materials to flow onto a surface of an object. A conventional slide-hopper-type, multilayer coating apparatus having a slide/extrusion hopper is adapted for dispensing a liquid composition onto a moving object. Such coating apparatuses generally can be categorized into a slide-rolling-edge type and a slide-curtain type.
China Patent Application No. 01100242.5 discloses a slide rolling edge type, multilayer coating apparatus and a slide curtain type, multilayer coating apparatus. In accordance with that application and referring to FIG. 3, the slide rolling edge type, multilayer coating apparatus 10 is illustrated. The slide rolling edge type, multilayer coating apparatus 10 includes a slide hopper 16 and a roller spindle 34. An object 12 to be coated is wound on the outer circumference of the roller spindle 34 and is driven to jointly rotate with the roller spindle 34. Coating materials 14A, 14B and 14C are forced to flow from corresponding material containers (not shown) to corresponding cavities 18, 20 and 22 by corresponding pumps (not shown). The coating materials 14A, 14B and 14C extend breadthwise to a predetermined width. The coating materials 14A, 14B and 14C are extruded through corresponding slots 24, 26 and 28. The coating materials 14A, 14B and 14C are then combined into a multilayer composite coating material 14 on a slide surface 30. The multilayer composite coating material 14 flows down along a projection portion 32 of the slide surface 30, forming a rolling coating material edge 36 bounded by the projection portion 32 and the moving object 12. Herein, an inhaled air removal device 38 is employed to remove the air brought/carried by the moving object 12 and to thereby stably sustain the rolling edge 36. Therefore, a multilayer coating film A is formed on the moving object 12.
FIG. 4 illustrates a slide curtain type coating apparatus 10′, as per the above-referenced application. The slide curtain type coating apparatus 10′ is similar to the slide rolling edge type, multilayer coating apparatus 10, as illustrated in FIG. 3. However, in the case of the slide curtain type coating apparatus 10′, the projection portion 32 of the slide surface is located farther away from the object 12 to be coated, when considered relative to the projection portion 32 of the slide rolling edge type coating device 10. The multilayer composite coating material 14 falls in the form of a curtain from the projection portion 32 of the slide surface 30 to the object 12. The multilayer composite coating material 14 is then extended to form a multilayer coating film A. A pair of guiding means 44 is disposed for guiding the falling multilayer composite coating material 14. An inhaled air removal device 46 is disposed and configured for removing the air brought/carried by the moving object 12 and for thereby promoting the formation of an even coating on the object 12.
The foregoing moving objects 12 to be coated may, for example, be ordinary papers, plastic films, resin half-tone papers or a composite papers, or potentially a flexible electronic substrate material. The coating materials 14A, 14B and 14C generally comprise emulsion, surface-active agents, and/or viscosity enhancing agents, as well as, of course, the primary coating material(s).
However, the aforementioned multilayer composite material 14 is formed on the slide surface 30 of the slide hopper 16 prior to being coated onto the object 12. Therefore, mutual diffusion between the coating materials 14A, 14B and 14C can inevitably occur. This mutual diffusion may adversely impair the coating quality.
Accordingly, a multilayer coating apparatus and a related method are needed in the art which can avoid the potential mutual diffusion of coating materials prior to their being coated on the object.